USN-5208-1: Linux kernel vulnerabilities

6 January 2022

Several security issues were fixed in the Linux kernel.

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Details

Nadav Amit discovered that the hugetlb implementation in the Linux kernel
did not perform TLB flushes under certain conditions. A local attacker
could use this to leak or alter data from other processes that use huge
pages. (CVE-2021-4002)

It was discovered that a race condition existed in the overlay file system
implementation in the Linux kernel. A local attacker could use this to
cause a denial of service (system crash). (CVE-2021-20321)

It was discovered that the NFC subsystem in the Linux kernel contained a
use-after-free vulnerability in its NFC Controller Interface (NCI)
implementation. A local attacker could possibly use this to cause a denial
of service (system crash) or execute arbitrary code. (CVE-2021-3760)

It was discovered that an integer overflow could be triggered in the eBPF
implementation in the Linux kernel when preallocating objects for stack
maps. A privileged local attacker could use this to cause a denial of
service or possibly execute arbitrary code. (CVE-2021-41864)

It was discovered that the KVM implementation for POWER8 processors in the
Linux kernel did not properly keep track if a wakeup event could be
resolved by a guest. An attacker in a guest VM could possibly use this to
cause a denial of service (host OS crash). (CVE-2021-43056)

It was discovered that the TIPC Protocol implementation in the Linux kernel
did not properly validate MSG_CRYPTO messages in some situations. An
attacker could use this to cause a denial of service (system crash) or
possibly execute arbitrary code. (CVE-2021-43267)

It was discovered that the ISDN CAPI implementation in the Linux kernel
contained a race condition in certain situations that could trigger an
array out-of-bounds bug. A privileged local attacker could possibly use
this to cause a denial of service or execute arbitrary code.
(CVE-2021-43389)

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Ubuntu Pro provides ten-year security coverage to 25,000+ packages in Main and Universe repositories, and it is free for up to five machines.

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Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 21.10
Ubuntu 21.04
Ubuntu 20.04

After a standard system update you need to reboot your computer to make
all the necessary changes.

ATTENTION: Due to an unavoidable ABI change the kernel updates have
been given a new version number, which requires you to recompile and
reinstall all third party kernel modules you might have installed.
Unless you manually uninstalled the standard kernel metapackages
(e.g. linux-generic, linux-generic-lts-RELEASE, linux-virtual,
linux-powerpc), a standard system upgrade will automatically perform
this as well.

References

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